Shell structures are architectural forms that are thin, curved, and often lightweight, designed to support loads while using minimal material. They can be found in various applications, from domes and roofs to bridges and tanks. The curved shape helps distribute forces evenly, making them strong and efficient. These structures are commonly made from materials like concrete, steel, or plastic, allowing for creative designs that can enhance both functionality and aesthetics. Famous examples include the Sydney Opera House and the Geodesic Dome, showcasing how shell structures can blend beauty with engineering excellence.